Polypropylene glycol esters of tetracarboxybutane and diglycolic acid



1 2,864,856 POLYPROPYLENE GLYCOL ESTERS F TETRA- CARBOXYBUTANE ANDDIGLYCOLIC ACID Alvin Howard Smith, Glendale, Mo., assignor to PetroliteCorporation, Wilmington, Del., a corporation of Delaware No Drawing.Original application August 6, 1954, Serial No. 448,387, now Patent No.2,819,221, dated January 7, 1958. Divided and this application April 10,1957, Serial No. 651,826

4 Claims. (Cl. 26i)484) This application is a division of my copendingapplication Serial No. 448,387, filed August 6, 1954, now Patent No.2,819,221.

My invention is concerned with new chemical products or compounds usefulas demulsifying agents in processes or procedures particularly adaptedfor preventing, breaking or resolving emulsions of the water-in-oil typeand particularly petroleum emulsions. My invention is also concernedwith the application of such chemical products or compounds in variousother arts and industries as well as with methods of manufacturing thenew chemical products or compounds which are of outstanding value indemulsification.

More specifically then, the present invention is concerned with an esteror ester mixture produced from certain diols in combination with twodifierent types of polycarboxy acids. The diol employed is apolypropylene glycol having an average molecular weight within the rangeof approximately 1600 to 2700. The preferred polypropylene glycol is onehaving a molecular weight of approximately 2000. For reasons which arewell known, such a product is not a single glycol, but represents amixture in which the molecular weight designation is in reality theaverage molecular weight of the mixture. However, this is the usual andconventional method of describing such polypropylene glycols.

The two acids employed are diglycolic acid and butane112:3:4-tetracarboxylic acid, commonly referred to as tetracarboxybutane.

The molal ratio of reactants are 1:4:4 in which the 1 representstetracarboxyl butane.

Manufacture of the herein described demulsifying agent is comparativesimple. In one procedure, tetracarboxy butane acid is simply esterifiedby any conventional means with 4 moles of polypropylene glycol with theelimination of water so as to yield a product which for the most partcorresponds to the following formula:

HGGOOROOGRCOOH HCOOOROOCRCOOH H--COOROOCROOOH H-C-COOROOORCOOH ice inwhich the characters have their previous significance and R' representsthe diglycolic acid residue.

What is said previously must be evaluated in light of esterificationreactions of the kind employed to produce polyester or alkyd resins andthe like. This means that when one mole of tetracarboxy butane isreacted with 4 moles of polypropylene glycol one does not obtainexclusively a compound of the kind described above, but rather a mixturein which the above may be the principal or major component, but thereare also present certain other derivatives as for example, fractionalesters having one or more carboxyl radicals and one or more hydroxylradicals.

What has been said previously applies with even greater force and effectwhen such reaction mass as previously described derived from one mole oftetracarboxy butane and 4 moles of polypropylene glycol is reactedfurther with 4 moles of diglycolic acid. The same limitation applies aswhen one attempts to obtain the first stageproduct of reaction. Not onlyis that true, but additional reactions corresponding to esters in linearpolymers, and also cross esterification, may take place so that actuallythe reaction mass is more complicated than has been indicated by theidealized formula noted above. For this reason the product obtained isbest described by the process by which it is derived from the abovenoted reactants in the ratios stated. Broadly speaking, one can employeither a single-step process in which all the ingredients are combinedat one time or a two-step process as previously suggested.

An obvious variant of the two-step process is to esterify 4 moles of thepolypropylene glycol with 4 moles of diglycolic acid and when theesterification is complete add EXAMPLE 1a About 30.0 pounds of a glycolhaving an average molecular weight of 1600 was charged into anesterification pot. This pot was a closed vessel made of 316 stainlesssteel, having cooling and heating coils, an agitator, a thermometer, anda condenser for disposing of Water and returning solvent reflux. 1.1pounds of tetracarboxybutane and 2.51 pounds of diglycolic acid wereadded. No solvent was used in this case. The mixture was heated to C.and held there for four hours, with constant stirring. During thisperiod, 0.6 pound of water was removed via the condenser. The productwas a viscous, dark amber fluid, containing a few specks of whitesediment.

In a similar procedure dried nitrogen gas was passed through the mixtureslowly with the only difference that there was, of course, no watercondensed. The same procedure has also been followed using a solventsuch as an aromatic petroleum solvent or a mixture of xylene and cymene.was employed in connection with the condenser and the water carried overand collected in the trap. Using this type of procedure the solvent waspermitted to remain in the product in some instances and in otherinstances Was removed by vacuum distillation. In some instances 7Patented Dec. 16, 1958 In such procedure a phase separating trap Forthis reason in the Table II 2116. Step Time, hrs.

SINGLE STEP ESTERIFICATION a small amount of toluene sulfonic acid wasemployed as a catalyst along with a solvent.

EXAMPLE 9a 37.7 pounds of polypropylene glycol 1700 were charged intothe above mentioned pot. 2.81 pounds of diglycolic acid was added andthe batch held? at 160 C. for four hours. During this time 0.75 poundofwater evolvedabout the theoretical amount expected if all the, glycolreacted. The batch was then cooled back to about 60 C. to allow additionof. 1.23. pounds of tetracarboxy Table III Temp., C.

Water Ev., lbs.

TWO-STEP ESTERIFICATION 1st Step Time, hrs.

Insofar that the products used, and particularly the tetracarboxybutane, are products of technical purity only it is obvious thatreference to molecular weight ratio is approximate and may vary Within areasonable degree one way or the other.

hereto attached claims reference is made to the approxi- Ex. No.

butane. The batch was then held at 170 C. for four more hours. Only atrace of water came off, and it was assumed that transesterification hadoccurred between the glycol ester and the tetracarboxy butane.

EXAMPLE 12a 1.34 pounds of tetracarboxy butane and 48.0 pounds ofpolypropylene l 2100 were-heated together at mate ratio of 1:4:4. Thecompleteness of reaction can 165 C. for'abo'ut four and one-half hours.11.2 pounds P Checked by F shmlnatlon thr 0112b (faction of 1 1 ofsolvent had been added to facilitate agitation and 4.5 lmatelytwo-thirds of the P Y ladlcals and D1 9 removal f water, About. 5 Poundf Water was mately all of the hydroxyl radicals or by a sapontficatlonevolved. The batch was cooled to allow addition of number as P SIY suggy the amount f 3.06 pounds of diglycolic acid, and then held at 180 C.Water ehmlnated;

for four hours. 0.36 pound of water evolved, indicat- Molecular Wmght 15a15O an pp f f fi 88 0 ing completion of the reaction bytransesterification and completeness of reactlon- Any Obviousequlvfllent f also direct esterification. These Examples 1a, 9a, andtetracarboxy butam y be mp y For example, 12a along with additionalexamples appear in Tables I, I have P p mflthyl d hyl sters and usedsuch II, and III following.

esters in preparing the herein described products with the eliminationof methyl or ethyl alcohol instead of water. One could also employ, ifavailable, anhydrides of tetracarboxy butane (either inter-molecular orintra molecular). This also would be true of the acyl chlorides. Methylor ethyl esters are of interest primarily solvent for the reason thatfractional distillation yields a comparatively pure ester from thetechnical grade of tetracarboxy butane.

As to the use of conventional emulsifying agents, reference is made toU. S. Patent No. 2,626,929, dated January 7, 1953, to De Groote, andparticularly to Part Three.

Everything that appears therein applies with equal force and effect tothe instant process, noting only that where reference is made to Example13/) in said text beginning in column 15 and ending in column 18,reference should be to Example 4a, herein described.

Another use for the esters herein described is in connection with theclarification of used lubricating oils. Lubricating oils fall into twogeneral classes; one being lubricating oil to which additives such asdetersives have been added. The other class represents a so-calledstraight hydrocarbon oil such as those exemplified by M01. Ratio, TCB:

Glycol: Xylene Diglycolic Diglycolic acid, lbs.

Table I Pounds 0710023071005500 Q 3 0 &L5 2 &3 0 &LL0 2 3 34443433444444mmwmmmmmmm mmmmm LLLzzlzzLLowna vwzp wz Tetraear-boxy- Butane,

62 4.4313 64 1 3O892m131099 LLLLLLQQLLLLLLQQ Ex. No.

lubricating oils derived from Pennsylvania Grade crude oil. Such usednon-additive type lubricating oils are reclaimed by a process which isessentially (1) filtration, (2) treatment with an alkali or sodiumsilicate, (3) a second filtration step, and finally distillation toremove volatile matter and bleaching by means of filtering earths orchars.

I have found that if a small amount of the esters of the kind hereindescribed, for instance as little as $4 of 1%, is added to the oil inthe initial step and the product heated to approximately 125 C. for twohours and then filtered the product becomes very clear in many instancesand the final bleaching step can be avoided.

I have found that the chemical compounds or reagents herein described,which are particularly desirable for use as demulsifiers, may also beused as a break inducer in doctor treatment of the kind intended tosweeten gasoline. See U. S. Patent No. 2,157,223, dated May 9, 1939, toSutton.

Having thus described my invention, what I claim as new and desire toobtain by Letters Patent, is

1. The step of esterifying a polypropyleneglycol having an averagemolecular weight of at least 1600 and not over 2700 with diglycolic acidand tetracar-boxy butane acid; the molal ratio of reactants being onepart of tetracarboxy butane to four parts each of polypropylene glycoland diglycolic acid; said reaction being conducted at a temperaturesufliciently high to evolve water and below the pyrolysis point ofreactants and reaction product with the elimination through reaction ofapproximately twothirds of the carboxyl radicals present andsubstantially all the hydroxyl radicals present.

2. The step of esterifying a polypropyleneglycol having an averagemolecular weight of about 2000 with diglycolic acid and tetracarboxybutane acid; the molal ratio of reactants being one part of tetracarboxybutane to four parts each of polypropylene glycol and diglycolic acid;said reaction being conducted at a temperature sufliciently high toevolve water and below the pyrolysis point of reactants and reactionproduct with the elimination through reaction of approximatelytwo-thirds of the carboxyl radicals present and substantially all thehydroxyl radicals present.

3. The process of claim 2 with the proviso that the procedure isconducted as a one-step process in absence of any added catalyst.

4. An esterified cogeneric mixture obtained by the process defined inclaim 1.

References Cited in the file of this patent UNITED STATES PATENTS2,442,073 De Groote et al May 25, 1948 2,599,538 Blair June 10, 19522,628,974 Sanderson Feb. 17, 1953 2,695,914 De Groote et a1 Nov. 30,1954

1. THE STEP OF ESTERIFYING A POLYPROPYLENEGLYCOL HAVING AN AVERAGEMOLECULAR WEIGHT OF AT LEAST 1600 AND NOT OVER 2700 WITH DIGLYCOLIC ACIDAND TETRACARBOXY BUTANE ACID; THE MOLAL RATIO OF REACTANTS BEING ONEPART OF TETRACARBOXY BUTANE TO FOUR PARTS EACH OF POLYPROPYLENE GLYCOLAND DIGLYCOLIC ACID; SAID REACTION BEING CONDUCTED AT A TEMPERATURESUFFICIENTLY HIGH TO EVOLVE WATER AND BELOW THE PYROLYSIS POINT OFREACTANTS AND REACTION PRODUCT WITH THE ELIMINATION THROUGH REACTION OFAPPROXIMATELY TWOTHIRDS OF THE CARBOXYL RADICALS PRESENT ANDSUBSTANTIALLY ALL THE HYDROXYL RADICALS PRESENT.
 4. AN ESTERIFIEDCOGENERIC MIXTURE OBTAINED BY THE PROCESS DEFINED IN CLAIM 1.